The purpose of this investigation is to develop test methodology for evaluation of the biologic properties of endodontic materials with the long-range goal of suggesting biologic standards and specifications. Presently the only tests which express the true tissue reactions to the materials under usage conditions are the expensive and cumbersome experimentations in primates or the "trial and error" in human patients. It is proposed to correlate specific screening and usage tests with the specific aim of developing adequate screening methods which will make future testing reliable and relevant and considerably less expensive than the usage tests. The proposed experimental systems and techniques for the correlation study are the following: 1. HeLa cells and human fibroblasts in tissue culture utilizing 51Cr release to measure cytotoxicity (Spangberg 1973). 2. Measurements of enhanced vascular permeability and cellular response in connective tissues in rats after intradermal injection of the material. 3. Evaluation of response to implants in soft tissue and bone in guinea pigs. 4. Evaluation of inflammatory response in remaining pulp tissue and in periapical tissue of monkeys. The methods of evaluation include radioisotope measurement, spectrophotometric, autoradiographic, SEM and electron probe, and histopathological techniques. The correlation of these tests will provide economical and relevant screening methods which may be used by manufacturers during their development of new products and for their quality control. Ultimately it will protect the patient population from inferior materials.